Most knowledge about the first solid bodies in the solar system comes from meteorites called carbonaceous chondrites, thought to be chunks of the first asteroids. Their chemical compositions are almost identical to the sun's — if you took all the hydrogen and helium out of the sun, you'd get the mineral ratios found in these bits of rock.

That similarity suggests the first asteroids formed directly from the disk of gas and dust that preceded the planets. The composition also suggests that

This article is only available to Science News subscribers. Already a subscriber? Log in now. Or subscribe today for full access.